I concur with David, it looks like dirty rollers. Roller transport is alright for paper as you can always re-do a print, but film is a once off.
That said although Dip 'n' Dunk machines are pretty much perfect for large scale developing with near perfect results, the one format that it isn't the greatest in, is 35mm film.
The problem lies with the way the film is put into the bath and held on the mechanism.
35 mm film is so long it has to be folded in half. Imagine a coat hanger with a tie hanging on it, that is pretty much how 35mm film is held.
The film is looped over a curved shape (at the top) with the emulsion facing outside, the ends of the film are clipped back to back on a special double film clip (at the bottom).
One of the hardest jobs in the lab was loading 35mm film without mishap. The problem is compounded by the fact you are working in an enclosed, small space. The temperature of the developer, in fact all of the baths, is 37.7C. This high temperature in an enclosed space, combined with the extreme humidity makes you hot and sweaty very quickly. The other interesting fact is that you do this in complete darkness, don't think about asking how one finds film when you drop a roll on the floor!
By the time you have loaded the 4th film on the rack, (they hold 4 rolls) your fingers can sometimes stick like anything to the film emulsion if you grab it in the wrong place. Once the rack is loaded with film you then remove it from it's resting place and carefully lift it up to catch the rack hangers. This is where 35mm film really gets interesting, the film is so long, the weighted ends swing a bit, sometimes they can get entangled with each other as they are only about 50mm apart, rarely, the top loop (centre of the film) turns vertical as it slips between the steel frame and the curved shape.
If the dryer is running a bit hot because they are developing humungus amounts of film and bumping the heater up quickens the film drying, you can have the centre frame of the film permanently shaped like a boomerang
Apart from that, Dip 'n' Dunk is terrific!
You ask, "were corner shops always this bad?" Yes they were, more or less. Film developing is an exact science, humans run things, the exact science part doesn't always happen. It is because of things like human error and sometimes sloppy practice, which is also human error, that I eventually decided to develop my own colour film about 25 years ago, still do.
I'm not suggesting that you should develop your own film, look around, see if you can find a local lab that has reasonably good throughput. Good throughput usually means there will be good maintenance, low throughput means the staff have a good chance of eventually becoming slack.
Mick.